libcang: Add missing function to libclang.map

[tstellar]

Summary

This function is marked with CINDEX_LINKAGE, but was never added to the
export list / linker script.

[tstellar]

Add missing ;

[jrtc27]

Thanks; I can confirm the test passes if and only if I apply this patch

clang/tools/libclang/libclang.map

global:
     clang_CompilationDatabase_getAllCompileCommands;
     clang_CompilationDatabase_getCompileCommands;
     clang_CompileCommand_getArg;
     clang_CompileCommand_getDirectory;
     clang_CompileCommand_getFilename;
     clang_CompileCommand_getMappedSourceContent;
     clang_CompileCommand_getMappedSourcePath;
     clang_CompileCommand_getNumArgs;
+    clang_CompileCommand_getNumMappedSources;
     clang_CompileCommands_dispose;
     clang_CompileCommands_getCommand;
     clang_CompileCommands_getSize;
     clang_Cursor_Evaluate;
     clang_Cursor_getArgument;
     clang_Cursor_getBriefCommentText;
     clang_Cursor_getCXXManglings;
     clang_Cursor_getCommentRange;